龍卷風是一種少見的(de)局地性、小尺度、突發性的(de)強(qiang)對(dui)流(liu)天(tian)氣,是在強(qiang)烈的(de)不穩定的(de)天(tian)氣狀(zhuang)況(kuang)下由空氣對(dui)流(liu)運動造成的(de)、強(qiang)烈的(de)、小范圍的(de)空氣渦(wo)旋。
從積雨云中(zhong)(zhong)(zhong)伸下的(de)(de)(de)猛烈旋(xuan)轉(zhuan)的(de)(de)(de)漏斗狀云樓。它有時(shi)稍伸即(ji)隱,有時(shi)懸掛空中(zhong)(zhong)(zhong)或(huo)觸(chu)及地(di)(di)(di)(di)(di)面(mian)(mian)。龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)漏斗云的(de)(de)(de)軸(zhou)一(yi)(yi)般(ban)(ban)垂(chui)直于(yu)(yu)地(di)(di)(di)(di)(di)面(mian)(mian),在(zai)發展的(de)(de)(de)后期,當上(shang)下層風(feng)速(su)相差(cha)較大(da)(da)時(shi),可(ke)(ke)(ke)成(cheng)傾斜狀或(huo)彎曲(qu)狀。其(qi)(qi)下部直徑最小(xiao)(xiao)的(de)(de)(de)只(zhi)有幾(ji)米(mi),一(yi)(yi)般(ban)(ban)為(wei)數(shu)(shu)百(bai)米(mi),最大(da)(da)可(ke)(ke)(ke)達(da)(da)千米(mi)以上(shang),上(shang)部直徑一(yi)(yi)般(ban)(ban)為(wei)數(shu)(shu)千米(mi),最大(da)(da)可(ke)(ke)(ke)達(da)(da)10公(gong)(gong)里(li)(li)。龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)的(de)(de)(de)尺度很(hen)(hen)小(xiao)(xiao),中(zhong)(zhong)(zhong)心氣(qi)(qi)壓(ya)很(hen)(hen)低(di),造(zao)成(cheng)很(hen)(hen)大(da)(da)的(de)(de)(de)水(shui)平氣(qi)(qi)壓(ya)梯度,從而(er)導(dao)致強(qiang)烈的(de)(de)(de)風(feng)速(su),中(zhong)(zhong)(zhong)心風(feng)速(su)可(ke)(ke)(ke)達(da)(da)100-200米(mi)/秒(miao)。由于(yu)(yu)氣(qi)(qi)流的(de)(de)(de)旋(xuan)轉(zhuan)力很(hen)(hen)強(qiang),常將地(di)(di)(di)(di)(di)面(mian)(mian)的(de)(de)(de)水(shui)、塵土(tu)、泥(ni)沙挾卷(juan)(juan)(juan)(juan)(juan)而(er)起,其(qi)(qi)破壞(huai)力變(bian)動(dong)范(fan)圍很(hen)(hen)大(da)(da),弱(ruo)者僅能卷(juan)(juan)(juan)(juan)(juan)起稻(dao)草(cao)捆和(he)(或(huo))衣物(wu)強(qiang)者可(ke)(ke)(ke)按樹倒屋,至把人(ren)、畜(chu)也(ye)一(yi)(yi)并升(sheng)起,經過水(shui)面(mian)(mian)時(shi)可(ke)(ke)(ke)吸水(shui)上(shang)升(sheng)如(ru)柱(zhu),(這時(shi)稱水(shui)龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)),所(suo)以龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)范(fan)圍雖小(xiao)(xiao),但造(zao)成(cheng)的(de)(de)(de)災情卻很(hen)(hen)嚴重。龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)的(de)(de)(de)移向、移速(su)是由其(qi)(qi)母云(產(chan)生(sheng)龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)的(de)(de)(de)積雨云)的(de)(de)(de)移動(dong)決(jue)定的(de)(de)(de),母云的(de)(de)(de)移速(su)通常為(wei)每小(xiao)(xiao)時(shi)40-50公(gong)(gong)里(li)(li),最快可(ke)(ke)(ke)達(da)(da)90-100公(gong)(gong)里(li)(li)。其(qi)(qi)移動(dong)路(lu)徑多呈直線,一(yi)(yi)般(ban)(ban)只(zhi)有幾(ji)公(gong)(gong)里(li)(li),個別(bie)可(ke)(ke)(ke)達(da)(da)數(shu)(shu)十公(gong)(gong)里(li)(li)。龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)是強(qiang)對(dui)流天(tian)氣(qi)(qi)的(de)(de)(de)產(chan)物(wu),常發生(sheng)于(yu)(yu)北緯20-50度地(di)(di)(di)(di)(di)帶(dai)低(di)層大(da)(da)氣(qi)(qi)層結具(ju)有很(hen)(hen)大(da)(da)對(dui)流不穩定的(de)(de)(de)地(di)(di)(di)(di)(di)區(qu)(qu),往往與鋒(feng)面(mian)(mian)、氣(qi)(qi)旋(xuan)或(huo)非(fei)熱帶(dai)性(xing)雷暴相伴隨(sui)。登陸后的(de)(de)(de)熱帶(dai)氣(qi)(qi)旋(xuan)移到中(zhong)(zhong)(zhong)緯趨向衰亡時(shi),也(ye)很(hen)(hen)易出現龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng),有時(shi)還可(ke)(ke)(ke)出現在(zai)熱帶(dai)地(di)(di)(di)(di)(di)區(qu)(qu)。根據龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)產(chan)生(sheng)的(de)(de)(de)地(di)(di)(di)(di)(di)區(qu)(qu)可(ke)(ke)(ke)分為(wei)陸龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(產(chan)生(sheng)在(zai)陸地(di)(di)(di)(di)(di)上(shang)空)和(he)水(shui)龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(產(chan)生(sheng)在(zai)海面(mian)(mian)或(huo)水(shui)面(mian)(mian)上(shang)空)。龍(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)很(hen)(hen)難預報,測雨雷達(da)(da)也(ye)未曾直接觀(guan)測到過。
龍(long)卷(juan)(juan)風(feng)(feng)(feng)(feng),是一種具有一定(ding)破壞力的(de)(de)自然現象。一般情(qing)況下,龍(long)卷(juan)(juan)風(feng)(feng)(feng)(feng)是一種氣(qi)旋。它在(zai)接觸地面時(shi),直(zhi)徑(jing)從幾(ji)(ji)米(mi)(mi)到幾(ji)(ji)百米(mi)(mi),平均為(wei)250米(mi)(mi)左右,最大(da)為(wei)1000米(mi)(mi)左右。在(zai)空中(zhong)直(zhi)徑(jing)可有幾(ji)(ji)千米(mi)(mi),最大(da)有10千米(mi)(mi)。極大(da)風(feng)(feng)(feng)(feng)速每小時(shi)可達150千米(mi)(mi)至450千米(mi)(mi),龍(long)卷(juan)(juan)風(feng)(feng)(feng)(feng)持續時(shi)間,一般僅幾(ji)(ji)分(fen)鐘,最長不過幾(ji)(ji)小時(shi)。所到之處(chu)萬物遭劫。龍(long)卷(juan)(juan)風(feng)(feng)(feng)(feng)漏斗(dou)狀中(zhong)心(xin)由(you)吸起(qi)的(de)(de)塵(chen)土(tu)和(he)凝聚(ju)的(de)(de)水氣(qi)組成(cheng)可見的(de)(de)“龍(long)嘴”。在(zai)海洋上,尤其是在(zai)熱帶,類似(si)的(de)(de)景象在(zai)發(fa)生稱為(wei)海上龍(long)卷(juan)(juan)風(feng)(feng)(feng)(feng)。
龍卷(juan)風通常是極其快速(su)的,每秒鐘100米(mi)的風速(su)不足(zu)為奇(qi),甚(shen)至達到(dao)每秒鐘175米(mi)以上(shang),比12級臺風還要大五、六(liu)倍。風的范圍(wei)很小,一(yi)般直徑只有(you)25~100米(mi),只在極少數的情況下直徑才達到(dao)一(yi)公(gong)里(li)以上(shang);從(cong)發生到(dao)消(xiao)失只有(you)幾分種,最多幾個(ge)小時。
大多(duo)數龍卷風(feng)在北半球是(shi)(shi)逆時針旋轉(zhuan),在南半球是(shi)(shi)順時針,也有(you)例外情況。卷風(feng)形成的確(que)切機理仍在研究中(zhong),一般認(ren)為是(shi)(shi)與大氣的劇(ju)烈活(huo)動(dong)有(you)關。
從19世紀以(yi)來,天氣預報的準確性大大提高,氣象雷達能夠監(jian)測到龍(long)卷風、颶風等各種(zhong)災(zai)害風暴。
龍(long)卷風(feng)經(jing)過之處(chu),常會(hui)發生拔(ba)起大樹、掀翻車輛、摧毀建筑物(wu)等現象,它往往使成(cheng)片莊稼、成(cheng)萬株果木(mu)瞬間被毀,令交(jiao)通(tong)中斷,房屋倒塌,人畜生命和經(jing)濟(ji)遭(zao)受損失。
龍(long)(long)卷(juan)風(feng)這種自然現象是(shi)云層中(zhong)雷(lei)暴的產(chan)物,具(ju)體(ti)的說(shuo),龍(long)(long)卷(juan)風(feng)就是(shi)雷(lei)暴巨大能量(liang)中(zhong)的一小部分在(zai)很(hen)小的區(qu)域內(nei)集中(zhong)釋放的一種形(xing)式(shi)。
龍(long)卷風的形成可以分(fen)為四個階(jie)段:
(1)大氣的(de)不穩定(ding)性產(chan)生強(qiang)烈(lie)的(de)上升(sheng)氣流(liu),由于急(ji)流(liu)中的(de)最(zui)大過(guo)境氣流(liu)的(de)影(ying)響,它被進(jin)一步(bu)加(jia)強(qiang)。
(2)由于與在垂直方(fang)向上速度和方(fang)向均有(you)切變的風(feng)相互作用,上升氣(qi)流在對流層的中部開(kai)始旋(xuan)轉,形成中尺度氣(qi)旋(xuan)。
(3)隨(sui)著(zhu)中尺度氣旋向地(di)面(mian)發展和向上(shang)伸展,它本身變細并增強。同(tong)時(shi),一個小面(mian)積的增強輔(fu)合,即初(chu)生的龍(long)卷在(zai)氣旋內部形成,產(chan)生氣旋的同(tong)樣過程,形成龍(long)卷核(he)心。
(4)龍(long)(long)(long)卷(juan)核(he)心中(zhong)的(de)旋(xuan)(xuan)轉(zhuan)與(yu)氣旋(xuan)(xuan)中(zhong)的(de)不同,它的(de)強度(du)足以使龍(long)(long)(long)卷(juan)一直伸展到地(di)面(mian)(mian)。當發展的(de)渦旋(xuan)(xuan)到達地(di)面(mian)(mian)高度(du)時,地(di)面(mian)(mian)氣壓急劇下(xia)降(jiang),地(di)面(mian)(mian)風速(su)急劇上升,形(xing)成(cheng)龍(long)(long)(long)卷(juan)風。
龍(long)(long)卷風(feng)發(fa)生(sheng)至(zhi)消(xiao)散的(de)時間短,作(zuo)用面積很小(xiao),以至(zhi)于現(xian)有(you)(you)的(de)探測儀器(qi)沒有(you)(you)足(zu)夠的(de)靈敏度來(lai)(lai)對(dui)龍(long)(long)卷風(feng)進行準確的(de)觀(guan)測。相對(dui)來(lai)(lai)說,多(duo)普(pu)勒(le)雷(lei)(lei)達(da)是(shi)比較有(you)(you)效和常(chang)用的(de)一種觀(guan)測儀器(qi)。多(duo)普(pu)勒(le)雷(lei)(lei)達(da)對(dui)準龍(long)(long)卷風(feng)發(fa)出(chu)的(de)微(wei)波束(shu),微(wei)波信(xin)號(hao)(hao)被龍(long)(long)卷風(feng)中的(de)碎屑和雨點反射(she)后重被雷(lei)(lei)達(da)接收。如果龍(long)(long)卷風(feng)遠離雷(lei)(lei)達(da)而去,反射(she)回(hui)(hui)的(de)微(wei)波信(xin)號(hao)(hao)頻率將向(xiang)低頻方向(xiang)移(yi)(yi)動;反之(zhi),如果龍(long)(long)卷風(feng)越來(lai)(lai)越接近雷(lei)(lei)達(da),則(ze)反射(she)回(hui)(hui)的(de)信(xin)號(hao)(hao)將向(xiang)高頻方向(xiang)移(yi)(yi)動。這(zhe)種現(xian)象被稱(cheng)為多(duo)普(pu)勒(le)頻移(yi)(yi)。接收到信(xin)號(hao)(hao)后,雷(lei)(lei)達(da)操作(zuo)人員就可以通過(guo)分析頻移(yi)(yi)數據(ju),計算出(chu)龍(long)(long)卷風(feng)的(de)速度和移(yi)(yi)動方向(xiang)。
雙極(ji)(ji)化技術的(de)出(chu)現對(dui)(dui)多(duo)(duo)普(pu)(pu)勒(le)天氣雷達(da)探(tan)測中氣旋和(he)龍卷(juan)(juan)進行了有力的(de)補(bu)充,全(quan)面提升了對(dui)(dui)龍卷(juan)(juan)微(wei)物理特征分析與預警預報水平(ping)。①由(you)于多(duo)(duo)普(pu)(pu)勒(le)天氣雷達(da)對(dui)(dui)較小尺(chi)度(du)的(de)龍卷(juan)(juan)渦旋探(tan)測需要(yao)具有良好(hao)的(de)空(kong)間(jian)分辨率(lv),然(ran)而(er)對(dui)(dui)雙極(ji)(ji)化探(tan)測而(er)言并不需要(yao)太高的(de)精度(du)。②雙極(ji)(ji)化特征信(xin)號(hao)(hao)不同于多(duo)(duo)普(pu)(pu)勒(le)特征信(xin)號(hao)(hao),由(you)于其是(shi)“各向同性”的(de),所以并不依賴(lai)于觀測角度(du)的(de)變化。③當龍卷(juan)(juan)在(zai)夜間(jian)發生或被大量(liang)降水包(bao)裹(guo)著難以通過多(duo)(duo)普(pu)(pu)勒(le)雷達(da)觀測發現時,雙極(ji)(ji)化信(xin)息更能有效地將其識別。
Wurman設計開(kai)發了第一(yi)部X波段移(yi)動(dong)式快(kuai)速掃描雷(lei)(lei)達(da) Rapid DOW,該雷(lei)(lei)達(da)每7秒可(ke)以(yi)完成(cheng)一(yi)次360°的(de)(de)體掃,在14秒的(de)(de)時間里可(ke)以(yi)探測到 12個波束(shu)范圍的(de)(de)數(shu)據,并且其距離(li)分辨率(lv)達(da)到11米,更易于對龍(long)卷三維結構進行研(yan)究(jiu)。從當前對龍(long)卷的(de)(de)探測技(ji)(ji)術來看,快(kuai)速掃描雷(lei)(lei)達(da)在時空尺(chi)度上對龍(long)卷觀測獨特(te)優勢。而美國計劃的(de)(de)下(xia)一(yi)代天(tian)氣雷(lei)(lei)達(da)網(wang)絡也定位為(wei)多功(gong)能相控陣雷(lei)(lei)達(da)。所以(yi)可(ke)見該技(ji)(ji)術未來必將成(cheng)為(wei)研(yan)究(jiu)該類天(tian)氣的(de)(de)主要手(shou)段。
多漩(xuan)(xuan)渦(wo)龍(long)(long)卷風(feng)(Multiple vortex)指(zhi)帶有兩股以上(shang)圍繞同一個(ge)中心旋轉的漩(xuan)(xuan)渦(wo)的龍(long)(long)卷風(feng)。多漩(xuan)(xuan)渦(wo)結(jie)構經常出現在劇烈的龍(long)(long)卷風(feng)上(shang),并且這些小漩(xuan)(xuan)渦(wo)在主龍(long)(long)卷風(feng)經過的地區上(shang)往往會(hui)造(zao)成更大的破壞(huai)。
水(shui)龍(long)(long)(long)卷(juan)(juan)(juan)(或稱海(hai)龍(long)(long)(long)卷(juan)(juan)(juan),英文:waterspout)可以簡單地(di)定義(yi)為水(shui)上(shang)的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng),通常意思是(shi)(shi)在水(shui)上(shang)的(de)(de)(de)非超級單體龍(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)。世(shi)界各地(di)的(de)(de)(de)海(hai)洋和湖(hu)泊等都可能出(chu)現水(shui)龍(long)(long)(long)卷(juan)(juan)(juan)。在美國,水(shui)龍(long)(long)(long)卷(juan)(juan)(juan)通常發(fa)(fa)生在美國東(dong)南部海(hai)岸(an),尤其在佛羅里達南部和墨西(xi)哥(ge)灣。水(shui)龍(long)(long)(long)卷(juan)(juan)(juan)雖在定義(yi)上(shang)是(shi)(shi)龍(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)的(de)(de)(de)一(yi)種(zhong),不過其破壞(huai)性要(yao)比最強大(da)的(de)(de)(de)大(da)草原龍(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)小,但是(shi)(shi)它們(men)仍然是(shi)(shi)相當(dang)危(wei)險的(de)(de)(de)。水(shui)龍(long)(long)(long)卷(juan)(juan)(juan)能吹翻小船,毀壞(huai)船只,當(dang)吹襲陸地(di)時就有更(geng)大(da)的(de)(de)(de)破壞(huai),并奪去(qu)生命。當(dang)水(shui)龍(long)(long)(long)卷(juan)(juan)(juan)很可能產生或在海(hai)岸(an)水(shui)域(yu)上(shang)已經(jing)看得(de)見的(de)(de)(de)時候,美國國家氣象(xiang)局將會經(jing)常發(fa)(fa)出(chu)特殊(shu)的(de)(de)(de)海(hai)上(shang)警告,或者當(dang)水(shui)龍(long)(long)(long)卷(juan)(juan)(juan)會向陸地(di)移動時發(fa)(fa)出(chu)龍(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)警告。
陸龍卷(juan)(英(ying)文:landspout,美(mei)國(guo)國(guo)家氣象局(ju)稱dust-tube tornado)用以(yi)描述一種(zhong)和中尺度氣旋沒有關(guan)聯的(de)龍卷(juan)風(feng)。陸龍卷(juan)和水龍卷(juan)有一些相(xiang)同(tong)的(de)特(te)點,例如強(qiang)(qiang)(qiang)度相(xiang)對較弱、持續(xu)時間短、冷凝形成(cheng)的(de)漏斗(dou)云(yun)較小(xiao)且經(jing)常不接觸(chu)地面等。雖然(ran)強(qiang)(qiang)(qiang)度相(xiang)對較弱,但陸龍卷(juan)依然(ran)會(hui)帶來(lai)強(qiang)(qiang)(qiang)風(feng)和嚴重(zhong)破壞。
火(huo)(huo)(huo)龍(long)卷(juan),非(fei)常罕(han)見(jian)的(de)(de)龍(long)卷(juan)風(feng)(feng)形(xing)態,由陸龍(long)卷(juan)與火(huo)(huo)(huo)焰的(de)(de)結合。2010年,位于南半(ban)球的(de)(de)巴西遭遇罕(han)見(jian)的(de)(de)干旱(han)少雨(yu)天氣,全國多(duo)地燃起了(le)(le)山火(huo)(huo)(huo)。8月24日(ri),巴西圣(sheng)保羅市一(yi)處火(huo)(huo)(huo)點刮起了(le)(le)龍(long)卷(juan)風(feng)(feng),形(xing)成了(le)(le)罕(han)見(jian)的(de)(de)火(huo)(huo)(huo)焰龍(long)卷(juan)風(feng)(feng)景觀。龍(long)卷(juan)風(feng)(feng)夾起火(huo)(huo)(huo)焰高達數米(mi),像一(yi)條(tiao)巨大的(de)(de)火(huo)(huo)(huo)龍(long)旋轉前進。這(zhe)條(tiao)“火(huo)(huo)(huo)龍(long)風(feng)(feng)”于24日(ri)被拍攝到(dao)。“火(huo)(huo)(huo)龍(long)”在燃燒的(de)(de)田野上(shang)飛(fei)舞高約數米(mi)高,阻斷了(le)(le)一(yi)條(tiao)公路。為了(le)(le)熄滅(mie)這(zhe)條(tiao)“火(huo)(huo)(huo)龍(long)”,當地出動了(le)(le)直升(sheng)機。
出現“火(huo)龍風”的(de)地區已經有3個月沒有下雨。異常干(gan)旱的(de)天氣和(he)強勁的(de)風勢助長了此(ci)處的(de)火(huo)勢。巴(ba)西全球電視臺報道稱,圣保(bao)羅地區的(de)空氣干(gan)燥程度已趕(gan)上了撒(sa)哈拉(la)沙漠。
龍卷風按它(ta)的破壞程(cheng)度不同(tong),分為0-5增強藤(teng)田(tian)級數,簡單來說就稱為EF級,由1971年芝加哥大學的藤(teng)田(tian)哲也博(bo)士所提出(chu)。
EF0級:風速在65-85英里(li)每(mei)小時,約合105-137公里(li)每(mei)小時,雖然較弱,但還是足(zu)以(yi)把(ba)樹枝吹(chui)斷,把(ba)較輕的碎片卷起來擊碎玻璃,一些煙囪會(hui)被(bei)吹(chui)斷。(出現幾率極(ji)高,53.5%)
EF1級:風速在每(mei)(mei)小時(shi)86-110英里(li)每(mei)(mei)小時(shi),約合138-177公里(li)每(mei)(mei)小時(shi),它們可以把(ba)屋頂吹(chui)走,把(ba)活動板(ban)房給(gei)吹(chui)翻(fan),一些較(jiao)輕的汽車會被吹(chui)翻(fan)或刮離(li)路面。(出現幾率(lv)較(jiao)高(gao),31.6%)
EF2級:風速在111-135英里每(mei)小(xiao)時,約合178-217公(gong)里每(mei)小(xiao)時,它(ta)們可以(yi)把沉重的甘草包吹(chui)出(chu)(chu)去幾(ji)百米遠,把一棵大樹連根拔起,貨車可以(yi)刮離路面(mian)。(出(chu)(chu)現幾(ji)率中等偏低,10.7%)
EF3級:風速在136-165英(ying)里每小(xiao)時,約合218-266公里每小(xiao)時,它(ta)們可以把一輛較重汽車吹(chui)(chui)翻,樹木被吹(chui)(chui)離地(di)面,房屋一大半(ban)被毀,火車脫離軌道。(出現(xian)幾率低,3.4%)
EF4級:風速在(zai)166-200英里每(mei)小時,約合267-322公里每(mei)小時,它(ta)們可以把一輛汽車刮飛,把一幢(chuang)牢固的房(fang)屋(wu)夷為平地,樹木被刮到幾百米高空(kong)。(出現幾率很(hen)低,0.7%)
EF5級:EF5級風速超過(guo)每小時200英里(li)每小時,也就是超過(guo)了322公里(li)每小時,房(fang)屋完全吹毀,汽車完全刮(gua)飛,路面(mian)上的(de)瀝(li)青也會被刮(gua)走,貨車、火車、列車全部脫離地面(mian)。(出現(xian)幾(ji)率較(jiao)低偏高(gao),20%—45%)
龍卷風并(bing)沒有(you)(you)EF6級。那是(shi)絕(jue)對不(bu)可(ke)能的(de)(de)(de),這(zhe)是(shi)根據(ju)物(wu)理和氣象(xiang)學推算出(chu)來(lai)的(de)(de)(de),所以,1999年(nian)5月3日俄克拉荷馬(ma)城的(de)(de)(de)龍卷風不(bu)是(shi)EF6級,而(er)是(shi)EF5級,但是(shi)電視臺也報道(dao)過當天超過每小時512公里(li)的(de)(de)(de)風速,而(er)且在一個雷達上估(gu)測(ce)到了318英里(li)每小時的(de)(de)(de)大(da)風,這(zhe)就表(biao)明龍卷風的(de)(de)(de)破壞(huai)力量(liang)很大(da),不(bu)要相信有(you)(you)EF6級龍卷風,那是(shi)虛構。
除此(ci)之外,龍卷風(feng)還可以分為4個形狀:
煙囪龍卷風:輪廓直,比較(jiao)粗壯(zhuang),強度(du)中等,一般在EF2—EF4級(ji)左(zuo)右。
繩形龍卷風:纖細(xi),輪廓教彎,強度弱,一般在EF0—EF2左右。
楔形龍卷風(feng):長度較(jiao)寬,可達1.5公里,寬度超過(guo)高(gao)度,強度強,一般在EF4—EF5左(zuo)右。
雙胞胎龍卷風:兩個龍卷風,有的粗,有的細(xi),強度不定。
全(quan)球除南極洲以外的(de)大洲都(dou)有龍(long)(long)卷(juan)(juan)風(feng)(feng)記錄,龍(long)(long)卷(juan)(juan)風(feng)(feng)主要發(fa)生(sheng)(sheng)在中(zhong)緯度地(di)區(qu),其中(zhong)美國發(fa)生(sheng)(sheng)最為(wei)(wei)頻繁,堪稱“龍(long)(long)卷(juan)(juan)王國”,被稱為(wei)(wei)“龍(long)(long)卷(juan)(juan)風(feng)(feng)之鄉(xiang)”,其發(fa)生(sheng)(sheng)的(de)龍(long)(long)卷(juan)(juan)風(feng)(feng)約占全(quan)球龍(long)(long)卷(juan)(juan)風(feng)(feng)總數的(de)75%;其次(ci)為(wei)(wei)加拿大;歐洲西部(bu)和(he)中(zhong)部(bu)、中(zhong)國、孟(meng)加拉國、日本、澳(ao)大利亞、新西蘭、南非(fei)和(he)阿根廷等國家或(huo)地(di)區(qu)龍(long)(long)卷(juan)(juan)風(feng)(feng)發(fa)生(sheng)(sheng)也較為(wei)(wei)頻繁。
年(nian)尺度特征美國(guo)(guo)(guo)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)平(ping)(ping)均(jun)每(mei)年(nian)有(you)(you)1000多個(ge)(ge)(ge)(ge)(1991—2010年(nian)間,平(ping)(ping)均(jun)為(wei)1253個(ge)(ge)(ge)(ge)/年(nian))。其(qi)(qi)(qi)次(ci)為(wei)加拿大(da),記(ji)(ji)錄(lu)到(dao)的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)平(ping)(ping)均(jun)約(yue)70個(ge)(ge)(ge)(ge)/年(nian),估計實際發生的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)平(ping)(ping)均(jun)約(yue)150個(ge)(ge)(ge)(ge)/年(nian)。歐洲(zhou)平(ping)(ping)均(jun)觀(guan)測到(dao)的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)大(da)約(yue)有(you)(you)330個(ge)(ge)(ge)(ge)/年(nian),其(qi)(qi)(qi)中陸(lu)(lu)(lu)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)170個(ge)(ge)(ge)(ge),水龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)160個(ge)(ge)(ge)(ge),而實際發生的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)大(da)約(yue)有(you)(you)700個(ge)(ge)(ge)(ge)/年(nian),其(qi)(qi)(qi)中陸(lu)(lu)(lu)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)300個(ge)(ge)(ge)(ge),水龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)390個(ge)(ge)(ge)(ge)。歐洲(zhou)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)多發生于英國(guo)(guo)(guo)、德國(guo)(guo)(guo)、法(fa)國(guo)(guo)(guo)和(he)西(xi)(xi)班(ban)牙:英國(guo)(guo)(guo)(1981—2010年(nian)間)平(ping)(ping)均(jun)每(mei)年(nian)大(da)約(yue)有(you)(you) (47.2±10.5)個(ge)(ge)(ge)(ge)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng),其(qi)(qi)(qi)中陸(lu)(lu)(lu)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)(36.5±10.1)個(ge)(ge)(ge)(ge),水龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)(12.7±2.8)個(ge)(ge)(ge)(ge);法(fa)國(guo)(guo)(guo)平(ping)(ping)均(jun)每(mei)年(nian)有(you)(you)15~20個(ge)(ge)(ge)(ge)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)。亞(ya)洲(zhou)的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)主(zhu)(zhu)要(yao)(yao)發生在中國(guo)(guo)(guo)、日本(ben)、印度和(he)孟加拉國(guo)(guo)(guo):中國(guo)(guo)(guo)平(ping)(ping)均(jun)每(mei)年(nian)發生的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)有(you)(you)73個(ge)(ge)(ge)(ge);日本(ben)平(ping)(ping)均(jun)每(mei)年(nian)發生20.5個(ge)(ge)(ge)(ge)陸(lu)(lu)(lu)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)和(he)4.5個(ge)(ge)(ge)(ge)水龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan);孟加拉國(guo)(guo)(guo)平(ping)(ping)均(jun)每(mei)年(nian)發生的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)有(you)(you)2個(ge)(ge)(ge)(ge)。大(da)洋洲(zhou)的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)主(zhu)(zhu)要(yao)(yao)發生在澳(ao)大(da)利(li)(li)亞(ya)和(he)新(xin)(xin)西(xi)(xi)蘭:澳(ao)大(da)利(li)(li)亞(ya)平(ping)(ping)均(jun)每(mei)年(nian)發生的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)有(you)(you)29個(ge)(ge)(ge)(ge),新(xin)(xin)西(xi)(xi)蘭平(ping)(ping)均(jun)每(mei)年(nian)發生的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)有(you)(you)17個(ge)(ge)(ge)(ge)。南美洲(zhou)的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)多發于阿根廷中部的(de)(de)(de)潘帕斯(si)草原:阿根廷平(ping)(ping)均(jun)每(mei)年(nian)記(ji)(ji)錄(lu)到(dao)的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)大(da)概有(you)(you)10個(ge)(ge)(ge)(ge);巴西(xi)(xi)、智利(li)(li)和(he)烏拉圭也有(you)(you)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)的(de)(de)(de)記(ji)(ji)錄(lu),巴西(xi)(xi)平(ping)(ping)均(jun)每(mei)年(nian)記(ji)(ji)錄(lu)到(dao)的(de)(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(juan)(juan)風(feng)(feng)有(you)(you)3個(ge)(ge)(ge)(ge)。
美國的(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)多(duo)發(fa)(fa)(fa)于(yu)(yu)(yu)春(chun)(chun)(chun)季(ji)(ji)(ji),其(qi)(qi)(qi)次(ci)為夏(xia)(xia)(xia)季(ji)(ji)(ji),冬(dong)季(ji)(ji)(ji)最少(shao)發(fa)(fa)(fa)生。歐洲的(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)主(zhu)要發(fa)(fa)(fa)生在夏(xia)(xia)(xia)季(ji)(ji)(ji),其(qi)(qi)(qi)次(ci)為秋季(ji)(ji)(ji):英國龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)主(zhu)要發(fa)(fa)(fa)生在秋季(ji)(ji)(ji)(9—11月(yue)(yue)),其(qi)(qi)(qi)次(ci)為夏(xia)(xia)(xia)季(ji)(ji)(ji)(6—8月(yue)(yue)),11月(yue)(yue)為龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)發(fa)(fa)(fa)生最多(duo)月(yue)(yue);德國2/3的(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)發(fa)(fa)(fa)生在6—8月(yue)(yue),其(qi)(qi)(qi)中(zhong)7月(yue)(yue)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)發(fa)(fa)(fa)生頻率達(da)27%;法國的(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)多(duo)發(fa)(fa)(fa)于(yu)(yu)(yu)春(chun)(chun)(chun)季(ji)(ji)(ji)和(he)(he)夏(xia)(xia)(xia)季(ji)(ji)(ji),8月(yue)(yue)發(fa)(fa)(fa)生最多(duo);西班牙的(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)多(duo)發(fa)(fa)(fa)于(yu)(yu)(yu)暖季(ji)(ji)(ji),明顯的(de)(de)趨(qu)向于(yu)(yu)(yu)秋季(ji)(ji)(ji)。澳大(da)利亞的(de)(de)龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)多(duo)發(fa)(fa)(fa)于(yu)(yu)(yu)初(chu)春(chun)(chun)(chun)和(he)(he)夏(xia)(xia)(xia)季(ji)(ji)(ji),其(qi)(qi)(qi)次(ci)為初(chu)冬(dong)。中(zhong)國龍(long)(long)(long)卷(juan)(juan)(juan)(juan)風(feng)發(fa)(fa)(fa)生的(de)(de)季(ji)(ji)(ji)節變化特征明顯,主(zhu)要集中(zhong)在春(chun)(chun)(chun)夏(xia)(xia)(xia)兩(liang)季(ji)(ji)(ji),尤(you)以7月(yue)(yue)和(he)(he)8月(yue)(yue)最多(duo),兩(liang)月(yue)(yue)約(yue)占全年(nian)總數的(de)(de)50%以上。日本56%的(de)(de)陸龍(long)(long)(long)卷(juan)(juan)(juan)(juan)發(fa)(fa)(fa)生在7—10月(yue)(yue),其(qi)(qi)(qi)中(zhong)9月(yue)(yue)最為頻繁,3月(yue)(yue)最少(shao);水龍(long)(long)(long)卷(juan)(juan)(juan)(juan)主(zhu)要發(fa)(fa)(fa)生在9—10月(yue)(yue),10月(yue)(yue)最多(duo)。
美(mei)國的(de)(de)(de)佛羅(luo)里達州(zhou)(zhou)(zhou)和(he)(he)(he)(he)中南(nan)(nan)(nan)部(bu)(bu)(bu)(bu)(bu)平原(yuan)是龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)的(de)(de)(de)高發(fa)區(qu)(qu),中南(nan)(nan)(nan)部(bu)(bu)(bu)(bu)(bu)平原(yuan)稱(cheng)為“龍(long)(long)卷(juan)(juan)(juan)走廊”,其范圍一般指從德(de)克薩斯州(zhou)(zhou)(zhou)中部(bu)(bu)(bu)(bu)(bu)向北(bei)(bei)到愛荷華州(zhou)(zhou)(zhou)北(bei)(bei)部(bu)(bu)(bu)(bu)(bu),以(yi)(yi)及(ji)從堪薩斯州(zhou)(zhou)(zhou)中部(bu)(bu)(bu)(bu)(bu)和(he)(he)(he)(he)內布拉(la)斯加(jia)(jia)東(dong)(dong)(dong)(dong)部(bu)(bu)(bu)(bu)(bu)到俄亥俄西(xi)(xi)部(bu)(bu)(bu)(bu)(bu)的(de)(de)(de)區(qu)(qu)域(yu)。英國的(de)(de)(de)龍(long)(long)卷(juan)(juan)(juan)主要發(fa)生(sheng)于英格蘭的(de)(de)(de)東(dong)(dong)(dong)(dong)部(bu)(bu)(bu)(bu)(bu)和(he)(he)(he)(he)南(nan)(nan)(nan)部(bu)(bu)(bu)(bu)(bu)以(yi)(yi)及(ji)海(hai)峽群島周邊。德(de)國的(de)(de)(de)龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)(duo)發(fa)于沿海(hai)和(he)(he)(he)(he)丘陵(ling)地(di)(di)區(qu)(qu)。法國的(de)(de)(de)龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)(duo)發(fa)于西(xi)(xi)北(bei)(bei)部(bu)(bu)(bu)(bu)(bu)、南(nan)(nan)(nan)部(bu)(bu)(bu)(bu)(bu)和(he)(he)(he)(he)東(dong)(dong)(dong)(dong)部(bu)(bu)(bu)(bu)(bu)。西(xi)(xi)班牙的(de)(de)(de)龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)(duo)發(fa)于地(di)(di)中海(hai)區(qu)(qu)域(yu)和(he)(he)(he)(he)加(jia)(jia)的(de)(de)(de)斯灣附近(jin)省份。中國龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)一般多(duo)(duo)發(fa)生(sheng)在(zai)(zai)中東(dong)(dong)(dong)(dong)部(bu)(bu)(bu)(bu)(bu)地(di)(di)形相對(dui)平坦(tan)的(de)(de)(de)平原(yuan)地(di)(di)區(qu)(qu),平原(yuan)多(duo)(duo)于山(shan)區(qu)(qu);從區(qu)(qu)域(yu)尺度來看,長江(jiang)(jiang)三角(jiao)洲、蘇(su)北(bei)(bei)、魯(lu)西(xi)(xi)南(nan)(nan)(nan)、豫東(dong)(dong)(dong)(dong)等(deng)(deng)平原(yuan)、湖沼區(qu)(qu)以(yi)(yi)及(ji)雷(lei)州(zhou)(zhou)(zhou)半島等(deng)(deng)地(di)(di)都是龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)的(de)(de)(de)易(yi)發(fa)區(qu)(qu);從省級行政單元尺度來看,江(jiang)(jiang)蘇(su)省、安徽省、廣東(dong)(dong)(dong)(dong)省、河(he)(he)南(nan)(nan)(nan)省、湖北(bei)(bei)省是龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)(duo)發(fa)的(de)(de)(de)省份,黑龍(long)(long)江(jiang)(jiang)省、河(he)(he)北(bei)(bei)省、浙江(jiang)(jiang)省、江(jiang)(jiang)西(xi)(xi)省和(he)(he)(he)(he)湖南(nan)(nan)(nan)省等(deng)(deng)省份龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)的(de)(de)(de)發(fa)生(sheng)頻次較高。1961—1993年間日(ri)本(ben)的(de)(de)(de)陸(lu)龍(long)(long)卷(juan)(juan)(juan)和(he)(he)(he)(he)水(shui)龍(long)(long)卷(juan)(juan)(juan)主要發(fa)生(sheng)在(zai)(zai)沿海(hai)地(di)(di)區(qu)(qu),而關東(dong)(dong)(dong)(dong)地(di)(di)區(qu)(qu)大(da)量龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)遠(yuan)離沿海(hai)區(qu)(qu)域(yu)。大(da)洋洲的(de)(de)(de)龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)主要發(fa)生(sheng)在(zai)(zai)澳(ao)大(da)利(li)亞和(he)(he)(he)(he)新西(xi)(xi)蘭。澳(ao)大(da)利(li)亞的(de)(de)(de)龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)主要發(fa)生(sheng)于東(dong)(dong)(dong)(dong)南(nan)(nan)(nan)部(bu)(bu)(bu)(bu)(bu)和(he)(he)(he)(he)西(xi)(xi)南(nan)(nan)(nan)部(bu)(bu)(bu)(bu)(bu)。南(nan)(nan)(nan)美(mei)洲的(de)(de)(de)龍(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)(duo)發(fa)于阿根(gen)廷中部(bu)(bu)(bu)(bu)(bu)的(de)(de)(de)潘帕斯草原(yuan)。巴西(xi)(xi)龍(long)(long)卷(juan)(juan)(juan)多(duo)(duo)發(fa)于南(nan)(nan)(nan)部(bu)(bu)(bu)(bu)(bu)和(he)(he)(he)(he)東(dong)(dong)(dong)(dong)南(nan)(nan)(nan)部(bu)(bu)(bu)(bu)(bu)。
我國(guo)大部(bu)分省(區、市)都(dou)有龍(long)卷風(feng)的(de)(de)蹤(zong)跡,主(zhu)要發(fa)生(sheng)在我國(guo)東(dong)部(bu)平原地區,1991年(nian)(nian)-2014年(nian)(nian),我國(guo)平均每年(nian)(nian)有43個龍(long)卷風(feng),其中(zhong)江蘇和廣東(dong)最多(duo),年(nian)(nian)均龍(long)卷風(feng)分別為5.5個和4.8個。春季(ji)、夏季(ji)是龍(long)卷風(feng)的(de)(de)多(duo)發(fa)季(ji)節,4-8月龍(long)卷風(feng)占全年(nian)(nian)的(de)(de)92%。
龍卷(juan)風(feng)(feng)是一種破(po)壞力極強的(de)(de)小尺度(du)天氣(qi)現象,直徑一般在100米(mi)(mi)以下,強龍卷(juan)可(ke)達幾百米(mi)(mi)到(dao)1千(qian)米(mi)(mi)左(zuo)右。相比于(yu)臺風(feng)(feng)、副高這(zhe)些天氣(qi)系統中的(de)(de)“大塊頭”,龍卷(juan)風(feng)(feng)絕(jue)對屬于(yu)“小個子”。而當前我們的(de)(de)氣(qi)象臺站不夠密集,以至于(yu)龍卷(juan)風(feng)(feng)經(jing)常躲過氣(qi)象監測的(de)(de)“法(fa)眼”。
龍(long)卷風(feng)強對(dui)流天氣往往生成(cheng)很突然,對(dui)某一地區的影響(xiang)時(shi)間(jian)也相對(dui)較(jiao)短,“生命史”只有十幾分鐘到(dao)個把小時(shi)。因此(ci),要提前(qian)24小時(shi)或是48小時(shi)預報局部地區的強對(dui)流天氣也就非常困難了。
龍卷風等強對流天氣的生成和(he)發(fa)展(zhan)需要衡量(liang)綜合大氣條件(jian),而(er)這些條件(jian)往(wang)往(wang)是難以預(yu)料、不確(que)切的,再加上不同(tong)地區之間各不相同(tong)的地形因素,也進一步增加了準確(que)監測、預(yu)報的難度。
(1)龍(long)(long)卷(juan)風發生是(shi)和強烈發展的(de)(de)(de)(de)積雨云聯系(xi)在(zai)(zai)一起的(de)(de)(de)(de),也就是(shi)通(tong)常所(suo)說的(de)(de)(de)(de)雷(lei)雨云。龍(long)(long)卷(juan)風出(chu)現(xian)時(shi)天空(kong)往往烏天黑地(di)(di)(云層(ceng)低而深厚、亮度(du)差)、電閃雷(lei)鳴、風雨交加。以春未到秋初最常見(jian),在(zai)(zai)一天中以下(xia)(xia)午至傍(bang)晚(wan)和凌(ling)晨(chen)至早晨(chen)出(chu)現(xian)最多。當看到天空(kong)有(you)(you)類似的(de)(de)(de)(de)癥兆就要引起注意。人群應立刻(ke)離開危險房屋、活動場所(suo)或(huo)其他簡易臨時(shi)住處,到附近比較堅固的(de)(de)(de)(de)房屋內躲避(bi)。在(zai)(zai)公共場所(suo),要服(fu)從指揮(hui),有(you)(you)秩序地(di)(di)向指定(ding)地(di)(di)點疏(shu)散。躲避(bi)龍(long)(long)卷(juan)風最為安全(quan)的(de)(de)(de)(de)地(di)(di)方是(shi)位于地(di)(di)下(xia)(xia)的(de)(de)(de)(de)空(kong)間或(huo)場所(suo)(如(ru)地(di)(di)下(xia)(xia)室或(huo)半地(di)(di)下(xia)(xia)室),地(di)(di)面上(shang)所(suo)有(you)(you)建筑物此時(shi)都不是(shi)安全(quan)躲避(bi)的(de)(de)(de)(de)場所(suo)。
(2)在野外(wai)遇到(dao)(dao)龍(long)卷(juan)風襲擊時(shi),不必驚慌失措,應迅(xun)速朝龍(long)卷(juan)風移(yi)動(dong)方(fang)向(xiang)的垂(chui)直方(fang)向(xiang)跑動(dong),伏于低(di)洼(wa)地面、溝渠等,但要(yao)遠離大(da)樹、電(dian)線桿、廣(guang)告牌(pai)、圍墻等,以免(mian)被(bei)砸(za)、被(bei)壓或發生觸電(dian)事故(gu)。如(ru)在汽車(che)中,應及時(shi)離開,到(dao)(dao)低(di)洼(wa)地躲避,因為汽車(che)本身(shen)沒有(you)防御(yu)龍(long)卷(juan)風能力,一旦汽車(che)和人同時(shi)被(bei)龍(long)卷(juan)風卷(juan)起,危害(hai)更(geng)大(da)。
(3)在家遇到龍(long)卷風(feng)(feng)時,遠離(li)和龍(long)卷風(feng)(feng)同方(fang)(fang)向的(de)窗、門(men)、房(fang)屋的(de)外(wai)圍墻壁,盡可能在龍(long)卷風(feng)(feng)相(xiang)反方(fang)(fang)向角落(luo)或(huo)比較堅固的(de)小房(fang)間抱頭蹲下,保護好自己(ji)的(de)頭部。在樓(lou)上,特別是(shi)農(nong)村的(de)樓(lou)房(fang)內(nei),應(ying)立(li)即暫避到一樓(lou)比較堅固的(de)桌(zhuo)子底下或(huo)廁所、儲物間內(nei)。這是(shi)因(yin)為龍(long)卷風(feng)(feng)中心的(de)氣壓極(ji)低(di),容易被(bei)龍(long)卷風(feng)(feng)外(wai)吸、房(fang)屋倒(dao)塌而(er)殃及(ji)室(shi)內(nei)人員安(an)全。
(4)在遭遇龍(long)卷風(feng)和發生(sheng)(sheng)房屋倒塌、電(dian)桿折斷的(de)情況下,應及(ji)時(shi)(shi)切斷電(dian)源(yuan),以防觸電(dian)和引發火災(zai)事(shi)故(gu)。如果是化工生(sheng)(sheng)產企業遭受龍(long)卷風(feng)襲擊,應及(ji)時(shi)(shi)關閉有毒化學物(wu)(wu)品(pin)閥門,控制化學物(wu)(wu)品(pin)泄(xie)漏,防止污染源(yuan)向土壤和水面擴散(san),必要時(shi)(shi)組織(zhi)附近(jin)市(村)民緊急(ji)轉移。
(5)龍(long)卷(juan)(juan)風(feng)后(hou)自救(jiu)互(hu)(hu)救(jiu)。由于龍(long)卷(juan)(juan)風(feng)的(de)風(feng)力特(te)別大(da)(da),具有(you)巨大(da)(da)的(de)破(po)壞作(zuo)用,龍(long)卷(juan)(juan)經過的(de)區域內,房屋等(deng)建筑(zhu)物(wu)常會遭(zao)受不同程度的(de)破(po)壞,甚至發(fa)生倒塌(ta)。因此,受龍(long)卷(juan)(juan)影響(xiang)地(di)區的(de)群眾,尤其是家庭、鄰里之(zhi)間(jian)(jian)在災(zai)后(hou)第一(yi)時間(jian)(jian)的(de)自救(jiu)互(hu)(hu)救(jiu)可最大(da)(da)限度減少人員(yuan)傷亡。被埋(mai)壓(ya)(ya)人員(yuan)要保持清醒(xing)頭腦,盡(jin)(jin)快想(xiang)法脫(tuo)離險境,如果不能自我脫(tuo)險時,應盡(jin)(jin)量創造和擴大(da)(da)安全(quan)生存(cun)空間(jian)(jian),減少對(dui)身(shen)體(ti)的(de)擠壓(ya)(ya),特(te)別是對(dui)腹部以(yi)(yi)上身(shen)體(ti)部位的(de)壓(ya)(ya)物(wu)要清除或移開,加強對(dui)頭部及口、鼻等(deng)器(qi)官的(de)自我保護,等(deng)待救(jiu)援。救(jiu)援時要講(jiang)究(jiu)方法,首先應使被救(jiu)者(zhe)暴露頭部,保持呼(hu)吸暢通,如有(you)窒(zhi)息,應立即進(jin)行人工呼(hu)吸。其次不可生拉硬(ying)扯或使用利(li)器(qi)硬(ying)挖被埋(mai)者(zhe),以(yi)(yi)免(mian)造成進(jin)一(yi)步的(de)損傷,同時對(dui)傷重(zhong)者(zhe)及時送醫院搶(qiang)救(jiu)。